Two-dimensional electrophoresis is an effective way to analyze complex mixtures of proteins. Typically, two-dimensional electrophoresis involves separating the protein mixture by the intrinsic charge characteristics of the proteins, i.e., their isoelectric points, in a first dimension by a type of electrophoresis called isoelectric focusing, and then separating the protein mixture in a second dimension by electrophoresis. In the second-dimension electrophoresis, a gel strip containing the proteins separated in the first dimension is incubated in a buffer appropriate for the second-dimension electrophoresis, and applied to a second-dimension vertical or horizontal slab gel so that the proteins can be electrophoresed out of the first-dimension gel and into the second gel under appropriate conditions to separate the proteins on the basis of molecular mass.
The first-dimension electrophoresis, i.e., isoelectric focusing, is usually performed on thin flat strips of polyacrylamide gel containing a covalently immobilized pH gradient, i.e., IPG gel strips. The IPG gel strips are commercially available in a dehydrated state and are rehydrated in an appropriate buffer before use. Currently, each IPG gel strip is rehydrated in a first gel carrier apparatus, and then handled and transferred by the user to a second gel carrier apparatus for isoelectric focusing (IEF) to separate the supplied proteins by isoelectric point.
A problem with the present processes and gel carrier apparatuses for IPG gel strip preparation and isoelectric focusing is that the IPG gel strips tend to be fragile, flimsy, and difficult to handle between the steps of rehydration and first dimension electrophoresis, as is commonly practiced at present time. Transferring the gel strip from a first gel carrier apparatus for rehydration to a second gel carrier apparatus for isoelectric focusing requires too much handling and hands-on-time for the first-dimension electrophoresis.